What to change the vaccine strategy against Covid-19 in France?
A French study, published this Monday and that Le Parisien was able to consult in preview, “confirms” the “uncommon” risk of myocarditis and pericarditis following a Pfizer or Moderna vaccination.
Such cardiac inflammation in the heart is most likely to occur in young men, in the week following the injection, and with the Moderna vaccine.
This work was carried out by the Epi-Phare group (National Agency for Medicines Safety and Health Insurance).
Their authors assure that they do not “call into question the benefit / risk ratio” of these two messenger RNA vaccines, by far the most widely used today in France, in particular because of the cardiac risks in the event of infection.
The study looked at all patients aged 12 to 50 years hospitalized for myocarditis or pericarditis from May 15 to August 31, respectively 919 and 917 cases.
60% of those in the "myocarditis" group and 36% of those in the "pericarditis" group were under 30 years of age.
"Particularly marked" risk in young men
Each patient was “matched” with 10 controls based on age, gender and department. By crossing this database with that of people vaccinated, the study reports that 33% of patients hospitalized for myocarditis and 23% of those treated for pericarditis had been immunized with Pfizer or Moderna during the previous three weeks. It was then possible to analyze the impact of vaccination.
Each time, the risk of suffering from one of these inflammations was "particularly marked" in men aged 12 to 29, in the week following the second injection. Regarding myocarditis, the study found 26.7 cases attributable to the vaccine for one million Pfizer doses and 131.6 for Moderna. That is, one case of myocarditis for 37,500 injections of Pfizer and one case for 7,600 doses of Moderna. The risk appears to be lower in women under 30, with - respectively - one case for 232,400 doses and one case for 26,800 doses, still within seven days of infection.
In men aged 30 to 50, there is one case for 211,000 doses of Pfizer and one for 37,700 doses of Moderna.
As for the risk of pericarditis, it "also appears marked" after a second dose of Moderna vaccine in young men under 30 (one case for 56,200 doses), but less than that of myocarditis.
Read also Pfizer or Moderna vaccination: should we be concerned about cases of myocarditis and pericarditis?
"The fact that these excess cases occur very quickly
(after the injection)
allows, among other arguments, to attribute this risk to the vaccine, because it cannot be due to chance", points out the epidemiologist Mahmoud Zureilk, director Epi-Phare and lead author of the study.
Moreover, the patient profile is not necessarily surprising.
In normal times, cases of myocarditis and pericarditis which occur in the population "are already more frequent in young men", indicates the professor of epidemiology and public health at the University of Versailles-Saint-Quentin-en-Yvelines.
New opinion from HAS expected
It is important to note that these patients generally recovered well. No deaths were reported during the study period, and the average hospital stay was between 2 and 4 days. This study "confirms the favorable clinical evolution of cases of myocarditis and pericarditis following vaccination" and "the number of cases appears infrequent in relation to the number of doses administered", reassure the authors. "The risk exists, but the benefit / risk balance remains favorable given that the vaccines are 90% effective against serious forms, even in young people", supports Mahmoud Zureik.
Still, these data reinforce the signal that had already appeared in the pharmacovigilance reports, published twice a month by the National Medicines Safety Agency (ANSM).
The one published on October 22 reported 13.9 cases of myocarditis per 100,000 injections in young men aged 18 to 24 and 7 per 100,000 in those aged 25 to 29.
Pharmacovigilance has investigated the cases of post-vaccination Moderna myocarditis, following the alert launched by the Scandinavian countries.
The French data "suggest a higher frequency in those under 30, in particular in men and after the 2nd injection".
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- Nicolas Berrod (@nicolasberrod) October 22, 2021
In view of these new data, should Moderna still be used in young men?
The question can all the more arise as several northern European countries have already decided to suspend it for this category.
For the moment, this vaccine can be offered to the entire population, but it was suspended for booster injections in mid-October, following a recommendation from the High Authority for Health.
This must issue new recommendations in the coming days.
